In WO2014/182160 an offshore vessel with a wellbore drilling installation is disclosed which comprises:                drilling tower,        a drill floor having a well center through which a drilling tubulars string can pass along a firing line,        at least one vertical trolley rail supported by the drilling tower,        a trolley, said trolley being guided along said at least one vertical trolley rail,        a main hoisting device adapted to move the trolley with the top drive device up and down along said at least one vertical trolley rails, and        a top drive device attached to the trolley, said top drive device comprising one or more top drive motors, e.g. electric top drive motors, and a rotary stem extending in the firing line and being driven by said one or more motors in order to impart rotary motion to a drilling tubulars string when connected to said top drive.        
In WO2014/178709 a wellbore drilling installation is disclosed wherein the trolley comprises a frame with a top frame member suspended from one or more winch driven cables of a main hoisting device, and with first and second vertical frame members that are each connected at an upper end thereof to the top frame member. These first and second vertical frame members depend from the top frame member at locations that are spaced apart from one another. The top drive device is attached to the frame via bails that are attached to the gearbox of the top drive and a hook arrangement on the top frame member. Thereby the top drive device is supported by the frame independent from the first and second vertical members. These first and second vertical members carry at their lower ends a cross beam which supports, in an embodiment, a rotatable tubular stem via a drilling operations thrust bearing. The stem is adapted to be connected, via a threaded portion at its lower end, to the top end of a drilling tubulars string that passes along the firing line into the wellbore. The top drive device is connectable to the upper end of the tubular stem so that drilling can be performed by rotating the drilling tubulars string. The load of a drilling tubulars string is transmitted via the thrust bearing and the cross beam to the first and second vertical frame members and thereby to the top frame member that is suspended from the main hoisting device.
In WO2014/193228 a wellbore drilling installation for drilling a wellbore or other wellbore related activities is disclosed, which installation comprises a slip device system recessed in the drill floor with a first slip device and a second slip device, each adapted to clamp onto and support the load of a drilling tubulars string. Each slip device is movable between an operational position aligned with the firing line and a respective retracted position remote from the firing line. These respective retracted positions are on opposite sides from the firing line. Each of the first and second slip devices has a lateral opening allowing to disengage the slip device in its operational position from a drilling tubulars string in the firing line and move the slip device into its respective retracted position and vice versa.